AUTOMATIC CONTROL SYSTEMSprofsite.um.ac.ir/~karimpor/autocontrol/lec4_aut_con.pdf · AUTOMATIC...

Lecture 14

AUTOMATIC CONTROLAUTOMATIC CONTROLSYSTEMSSYSTEMSAli Karimpour

Associate ProfessorFerdowsi University of Mashhad

Ali Karimpour Apr 2013

Chapter 4

Lecture 4

The AVR Microcontroller


Chapter 4

Introduction to AVR CISC (Complex Instruction Set Computer)

Put as many instruction as you can into the CPURISC (Reduced Instruction Set Computer)

Reduce the number of instructions, and use your facilities in a more proper way.

RISC processors have a fixed instruction size. In AVR the instructions are 2 or 4 bytes. Reduce the number of instructions so higher speed. More than 95% of instructions are executed in 1

machine cycle. Use of high level language for programming.


Chapter 4

AVR structure

4

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31

Instruction Register

Instruction decoder

SREG: I T H S V N CZ


Chapter 4

AVR’s CPU

5

AVR’s CPU ALU 32 General Purpose

registers (R0 to R31) PC register Instruction decoder

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder



Chapter 4

Some simple instructions

There are some instructions for loading values, doing arithmetic and logic operations; such as:

LDI (Load Immediate), ADD, SUB, INC, DEC, AND, etc. LDI Rd, k % In high level language Rd = k ADD Rd,Rs % Rd = Rd + Rs SUB Rd,Rs % Rd = Rd – Rs IVC Rd % Rd=Rd+1 DEC Rd %Rd=Rd-1Write a program that calculates 19 + 95 CPU

PC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder


LDI R16, 19 ;R16 = 19

LDI R20, 95 ;R20 = 95

ADD R16, R20 ;R16 = R16 + R20


Chapter 4

R0 through R15 Only registers in the range R16 to R31 can be loadedimmediate. We cannot load a constant into the registers R0 to R15 directly. It would have to be loaded intoa valid register first then copied.To load the value of 10 into register zero (R0): LDI R16,10 ;R16=10

MOV R0,R16Copy contents of R16 to R0

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder



Chapter 4

Status Register (SREG)

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder


SREG:

CarryZero

NegativeoVerflow

SignN+VHalf carry

Temporary

Interrupt

H S V N CZTI•The Status Register contains information about the result of the most recently executed arithmetic instruction. •This information can be used for altering program flow in order to perform conditional operations. •This will in many cases remove the need for using the dedicated compare instructions, resulting in faster and more compact code.


Chapter 4

Status Register (SREG)

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder


SREG:

CarryZero

NegativeoVerflow

SignN+VHalf carry

Temporary

Interrupt

H S V N CZTI

• Bit 7(I): Global Interrupt Enable

• Bit 6(T): Bit Copy Storage

• Bit 5(H): Half Carry Flag• Bit 4(S): Sign Bit, S = N ⊕V• Bit 3(V): Two’s Complement Overflow Flag

• Bit 2(N): Negative Flag

• Bit 1(Z): Zero Flag

• Bit 0(C): Carry Flag


Chapter 4

Addresses Register (SREG)

CPUPC

ALU

registers

R1R0

R15

R2

…

R16R17

…

R30R31


Instruction decoder



Chapter 4

AVR different groups

Classic AVR e.g. AT90S2313, AT90S4433

Mega e.g. ATmega8, ATmega32, ATmega128

Tiny e.g. ATtiny13, ATtiny25

Special Purpose AVR e.g. AT90PWM216,AT90USB1287


Chapter 4

ATMEGA32 Features

12

High-performance, Low-power Atmel®AVR® 8-bit Microcontroller

131 Powerful Instructions – Most Single-clock Cycle Execution

32 × 8 General Purpose Working Registers 32Kbytes of In-System Self-programmable Flash

program memory (W/E: 10,000 times) 1024Bytes EEPROM (W/E: 100,000 times) Data retention: 20 years at 85°C/100 years at 25°C Programming of Flash, EEPROM, Fuses, and

Lock Bits through the JTAG Interface


Chapter 4

13

Operating Voltages – 2.7V - 5.5V for ATmega32L – 4.5V - 5.5V for ATmega32

Speed Grades 0 - 8MHz for ATmega32L 0 - 16MHz for ATmega32

Power Consumption at 1MHz, 3V, 25°C Active: 1.1mA Idle Mode: 0.35mA Power-down Mode: < 1μA

ATMEGA32 Features


Chapter 4

ATMEGA32 Pin Configurations

14


Chapter 4

ATMEGA32 Peripheral Features

15

Two 8-bit Timer/Counters and one 16-bit Four PWM Channels 8-channel, 10-bit ADC Programmable Serial USART Programmable Watchdog Timer with Separate On-

chip Oscillator On-chip Analog Comparator Internal Calibrated RC Oscillator External and Internal Interrupt Sources Six Sleep Modes: Idle, ADC Noise Reduction, Power-

save, Power-down, Standby and Extended Standby


Chapter 4

ATMEGA32 Pin Descriptions

16

GND Ground.

VCC Digital supply voltage.

Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port.

Port A (PA7..PA0) Port A is an 8-bit bi-directional I/O port.

Port C (PC7..PC0) Port C is an 8-bit bi-directional I/O port.Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port.


Chapter 4

ATMEGA32 Pin Descriptions

17

XTAL1 Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

RESET Reset Input.

AVCC AVCC is the supply voltage pin for Port A and the A/D Converter.

XTAL2 Output from the inverting Oscillator amplifier.

AREF AREF is the analog reference pin for the A/D Converter.


Chapter 4 ATMEGA32 Pin Descriptions

18

ADC0-7

Port A serves as the analog inputs to the A/D Converter.

Port A Pins Alternate Functions



19

XCK/T0T0 (Timer/Counter0 External Counter Input)XCK (USART External Clock Input/Output)

Port B Pins Alternate Functions

T1T1 (Timer/Counter1 External Counter Input) INT2/AINOAIN0 (Analog Comparator Positive Input)INT2 (External Interrupt 2 Input)



20

PD2INT0 (External Interrupt 0 Input)

Port D Pins Alternate Functions

PD3INT1 (External Interrupt 1 Input)

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